Liquid separators are known which separate oil droplets from an air flow. For this purpose, the liquid separator has a separating medium that is arranged in a housing. The housing comprises a housing cup and a housing lid. The housing lid has a thread with which the liquid separator is screwed onto a head. In the head there is an air conduit for the air-oil mixture and a purified air conduit for the purified air. Moreover, the head has an oil discharge. The lid is provided with an unfiltered air inlet as well as a purified air outlet. The unfiltered air inlet communicates with the air-oil mixture conduit. The purified air outlet of the liquid separator is connected to the purified air passage of the head. The oil droplets contained in the air flow to be purified are agglomerated by the separator medium to larger drops that flow downward on the inner side of the circular closed separating medium. The separated oil can exit the liquid separator through an oil drain and is discharged by the oil discharge of the head. The liquid separator has a seal that is arranged between the lid of the liquid separator and the head. When mounting the liquid separator on the head, the housing is screwed onto the head in such a way that a seal-tight connection is produced. Depending on the force applied for screwing the liquid separator onto the head, the seal is compressed more or less. When the pressing force is too small leakage may occur. When the screw-on torque of the filter housing is too great, the seal may become damaged or the required release torque is too high so that an element exchange is made difficult. Moreover, the liquid separator must be rotated several times about its own axis until a fixed connection is generated.
It is an object of the present invention to provide a liquid separator that can be mounted in a simple way and is reliable with regard to handling.